More specifically, the invention relates to an improvement to an apparatus intended to lay reinforcing elements intended to form the reinforcement positioned under the tread of a tire.
An apparatus of this type is known from the prior art and is described in detail in publication EP 248 301. An apparatus of this type allows the lengths of thread intended to form the reinforcement of the tire to be projected onto a receiving surface, in the manner of a whip lash.
FIG. 1 illustrates an apparatus of this type employing this principle. An apparatus such as this uses a thread 1 packaged, for example, in the form of a feed reel, not depicted. The apparatus projects lengths of thread onto a receiving surface (not depicted) which may consist of the surface of the tire or alternatively may consist of any other surface such as a crown-reinforcing ring intended to be transferred onto the tire preform or alternatively a flat surface intended to form a crown-reinforcing ply in the form of a semi-finished product.
The term “thread” is to be understood in its broadest sense, covering a monofilament, a multifilament, a twisted cord or a folded yarn or equivalent assembly, and for this to be true irrespective of the material of which the yarn is made or of the treatment it may undergo, for example a surface treatment to encourage it to bond closely with rubber, or alternatively, a rubberizing treatment encasing the said thread in a coat of rubber to allow it to adhere directly to the support when it is projected.
Said apparatus comprises:                feed means 11 for feeding thread 1 from a source of thread, a rotary conduit 2 fixed to a shaft 20 constituting the axis of rotation of the said conduit, so that the outer radial end 21 of the said conduit is directed substantially radially with respect to the axis of rotation, the said conduit receiving the thread 1 via its central end 22 which is the opposite end to the said outer radial end 21 arriving from the said feed means, the said thread leaving via the said outer radial end, the said feed means controlling the linear rate of advance of the thread inside the said rotary conduit,        means for rotating the said rotary conduit,        thread-cutting means (31, 24) acting on the thread in such a way as to release one length for each revolution of the said rotary conduit.        
For further details regarding the operation of this apparatus it is suggested that the aforementioned publication EP 248 301 be consulted.
This apparatus may further comprise a thread guide 4 to receive and guide the lengths of thread, as is also described in publication EP 248 301, and in publications EP 845 348 or EP 845 349.
One aspect of the invention relates to the cutting system used in this type of apparatus.
Indeed, it has been demonstrated that the length of thread deforms during its free travel under the action of the energy stored up at the time of cutting. This deformation is therefore liable to alter appreciably the configuration of the thread when it “lands” on the receiving surface.